KeePass has been recommended on this site several times as a password manager. One thing you should not overlook though is the ability to store text in its secure database.

For example, you can create a new entry called “Life Insurance Policy” and use the notes field to store your policy information. Additionally, you can use the built in expiration date reminder to notify you when your policy is about to expire.

Of course you can use this to store your bank/investing account numbers which you would probably have in the same entry as your respective login. However in the above example, you may not have a login so you would just need to store the notes.

Basically, anytime you need to store secure text, take a look at using your password manager program as it is designed to keep the data secure. While KeePass is the tool I prefer, I am sure other password manager programs can accomplish this as well.